Such seals for torque transmission devices are widely used in mechanical and automotive engineering. One use, for example, is for feeding servo medium to a device for the relative hydraulic angular adjustment of a camshaft of a valve train of an internal combustion engine. In such a device, disclosed in JP 04-252 814, the servo medium supply is effected via an outer web of a cylinder head of the internal combustion engine. The sealing of the torque transmission device is realized through the relatively large axial length of the sealing surface in the region of the passage through which the servo medium is fed and of an annular groove on the outer peripheral surface of the camshaft.
In other solutions provided by the prior art, sealing of the torque transmission device is accomplished by the use of sealing rings arranged on both sides of the passages or channels. However, such constructions have not only the drawbacks of complicated manufacturing, but, during operation of the device, it is also possible for these rings to "dig" into the opposing component or to produce undesired abrasion.
Prior art torque transmission devices have the general drawback that with increasing warming-up, the outer member having the bore expands to a greater extent than the body which extends with its outer peripheral surface in this bore. This is encountered, for example, if the outer member is made of an aluminum alloy and the body is made of a steel. Thus, with increasing temperature, the sealing gap between the parts to be sealed is disadvantageously enlarged. This leak effect is augmented by the fact that the viscosity of the servo medium decreases with rising temperatures. In addition, the thus improved rheological properties of the hydraulic medium also lead to increased leakage thereof.